Are you looking just to change individual menu items on a specific page, or within a specific category? Check out the UberMenu Conditionals Extension
Target Specific Pages (Menu Swapper)
To easily swap out different menus on specific pages, you can use my free Menu Swapper plugin. This plugin allows you to register new theme locations and then change out the theme location on any Page, Post, or Custom Post Type in WordPress (it won’t help on archive or taxonomy pages), without having to write any code.
For example, let’s say you use your “Main Menu” as the primary navigation menu on every page on your site. But on a landing page, you want a different set of menu items to appear, which are specific to that page. You would assign the “Main Menu” to your Primary theme location. Then on your landing page, you would configure the Menu Swapper to replace the menu in the Primary theme location with your special menu instead.
Target sections of a site (Conditional Menus)
Another plugin that is more robust than the Menu Swapper is the Conditional Menus plugin by Themify. This plugin has a nice interface for replacing the menu on more robust conditions than just a specific page.
If you are using this plugin with UberMenu v3.2.5 or earlier, you may need to comment out this line in
$args['theme_location'] = apply_filters( 'conditional_menus_theme_location', '', $new_menu, $args );
$args['theme_location'] = '';